Invar block.
Invar is an alloy of primarily iron (64%) and nickel (36%), known for is unusually low coefficient of thermal expansion. This makes it useful for precision instruments and measuring devices that should as much as possible remain the same size and shape at all times. This block would be excellent for smashing such a precision instrument into a tangle mess of broken gears and dials. It weighs about 13 pounds and appears to have been roughly cut with a large band saw.Source:eBay seller boss1Contributor:Theodore GrayAcquired:19 June, 2007Text Updated:20 June, 2007Price: $60Size: 10"Composition:FeNiCCr